All animals need to know what's going on in the world around them; thus, brain mechanisms have evolved to gather and organize sensory information, to build transient and sometimes enduring internal representations of the surroundings. Using relatively simple animals, and focusing primarily on olfaction, our unit combines electrophysiological, anatomical, behavioral, and other techniques to examine the ways intact neural circuits, driven by sensory stimuli, process information. In the past year our new research program has begun to address several questions, among them: What mechanisms, including the transient oscillatory synchronization of ensembles of neurons, underlie information coding and decoding? What neural mechanisms underlie the phenomenon of stimulus invariance (in which stimuli are perceived as the same, or of the same class, despite actual differences in orientation, intensity, and so forth)? How are multi-modal stimuli integrated into unified perceptions? And how are innate sensory preferences determined? Our work reveals basic mechanisms by which sensory information is transformed, stabilized, and compared as it makes its way through the nervous system.